Machineable steel and articles formed therefrom



able quantity avoids the deleterious Patented May 4, 1937 UNITED STATESPATENT OFFICE MACHINEABLE STEEL AND ARTICLES I FORMED THEREFROM Myinvention relates tobodies, such as screws,

Louis H. Winkler, Bethlehem Steel Pennsylvania Bethlehem, Pa., assignorto Company, a corporation of No Drawing. Application February 20, 1934,

Serial No. 712,138

6 Claims. (c1. 75-123) which involve as steps ,of their manufacture, up-

setting or cold forming,

tions.

and machining opera- My invention comprisesarticles of manufacture, suchas screws, of

rimmed steels containing percentages of sulphur sufiiciently great torender them easily machineable. This invention further comprises suchsteels themselves.

Relatively high sulphur contents have been used for some time ticularlyin screw sto sulphur content have widely used for various purposes.

in machining. steels, parck. Rimmed steels of low been long well knownand I have discovered that sulphur in large enough amounts to confereasy machineability, particularly for threading operations,

may be added to rimmed steel with beneficial results in the manufactureof such articles as screws. Such steels have excellent upsetting andcold forming properties and therefore they may be readily headed as, forexample, in screw manufacture.

When, prior to myinvention, relatively high contents of sulphur readymachineability frequently had surfaceseams, which caused were the usedfor conferring imperfections, such as difliculty in upsetting and coldforming operations and giving at times more or less unsatisfactoryproducts. To prevent or nullify these imperfections additions of somedeoxidant, aluminum for example, have been made,

but the resulting steel additions, frequently 5, as a consequence ofthese offered difliculties in machining. By my invention these obstaclesto upsetting, cold forming and machining are overcome. Because of thsurface or skin e rimming of the steel the is substantially free fromthe imperfections which have rendered upsetting operations diflicult andprisingly, the surface rimming, does the sulphur in tions. Obviously theuncertain and, rather surcondition, thus produced by not interfere .withthe action of facilitating the machining operaemployment of thispractic'e makes unnecessary the use of any considerofdeoxidants asheretofore and eflect of such additions on the machining qualities.

I employ steels having carbon contents up to 25%.. manganese up to .60%,and silicon preferably not exceeding .03%. The usual methods for makingrimmed steel additions are prefer are employed. Aluminum ably avoided.Sulphur is steels thus produced added to the steel in the ladle after ithas left the steel producing furnace, suflicient of this element beingadded to give a sulphur content in the finished steel of from .07% to.25%. Sulphur may be added in any desired form, as for example 5 asstick sulphur or as pyrites.

For wood screw stock I employ rimmed steel preferably containing carbonfrom .10% to 20%, and sulphur from .10% to .16%, although I haveobtained satisfactory results with sulphur as low 10 as .08% and as highas .18%. Such steels are readily adapted to upsetting operations andthey thread easily giving accurate threads free from appreciableimperfections.

Rimmed steels containing carbon .06% to .12% and sulphur .07% to havegiven good results in the manufacture of machine screws, the resultsbeing especially good with carbon .06% to 10% and sulphur .08% to .12%.In making machine screws with these steels standard meth- 20 ods ofmanufacture may be employed. The properties due to the rimming of thesteel facilitate the forming operations such'as upsetting and threadrolling without interfering with the effects of the sulphur in aidingthe machining operations such as shaving and slotting of the heads.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. Screw stock of rimmed steel containing carbon up'to 25%, and sulphur.07% to .25% and the balance consisting substantially of iron.

2. Wood screw stock of rimmed steel containing carbon .10% to .20% andsulphur .08% to r .18% and the balance consisting substantially of 30iron.-

3. Machine screw stock of rimmed steel containing carbon .06% to .10%and sulphur .07% to .14% and the balance consisting substantially of 40iron.

'4 A ,wood screw of rimmed steel containing carbon .10% to 20% andsulphur .07% to .25%

and the balance consisting substantially of iron. 5. A machine screw ofrimmed steel contain- 6. A machine screw of rimmed steel containingcarbon up to ,12% and sulphur .07% to'.25% and the .balance consistingsubstantially of iron.

LOUIS H. wmmna.

